"the type of this value must be known in this context" reoccurring

[lifthrasiir]

Regarding #2429, I have observed the same error occurring in the recent incoming (5f13e9c 2013-04-02 13:36:51 -0700):

use core::hashmap::linear::LinearMap;
fn main() {
    let mut map = LinearMap::new();
    let set_default = |k: int, v: int| {
        // N.B. we can't use match here due to the other bug #4666
        let insert =
            match map.find_mut(&k) {
                Some(vs) => { /*let vs: &mut ~[int] = vs;*/ vs.push(v); false }
                None => true
            };
        if insert { map.insert(k, ~[v]); }
    };
    set_default(1, 2);
    set_default(2, 3);
    set_default(1, 4);
    for map.each |&(&k, &v)| { io::println(fmt!("%? -> %?", k, v)); }
}

...resulting in:

t.rs:6:24: 6:26 error: the type of this value must be known in this context
t.rs:6             Some(vs) => vs.push(v),
                               ^~

It compiles (and works) correctly if we uncomment let vs: ... = vs; part.

[lifthrasiir]

Uh, I realized that the original bug refers to "duplicate errors", not an occurrence of the error itself. Marking this issue invalid.